1. Field of the Invention
The present invention relates to flat-form separation devices of the type used to effect a separation of two structures, such as the stages of a multi-stage rocket, that are temporarily adjoined to one another by the separation device. Separation of the temporarily joined structures is attained by explosively rupturing a frangible joint which extends along the length of the separation device between the two joined structures.
2. Related Art
Such separation devices are well-known and typically comprise a frangible joint within which is disposed an expansion device. The frangible joint connects a pair of joinder flanges, respective ones of which extend along laterally opposite sides of the frangible joint. Typically, the frangible joint has a channel extending there-through and within which the expansion device is disposed. The frangible joint further has a pair of grooves extending along the exterior thereof, one opposite each side of the channel, to provide a fracture seam. The expansion device typically comprises a deformable containment tube (in those cases in which it is desired that the products of the rupturing explosion not contaminate the environment) within which an elastomeric charge holder supports a linear explosive charge, typically a mild detonating fuse. The joinder flanges are secured to respective structures that are eventually to be separated, e.g., fairings or field joint adapters on a rocket, missile or payload platform, and the frangible,joint holds the respective structures together until the frangible joint is ruptured by detonation of the linear explosive charge.
A separation device as described above and comprised of a pair of half-sections which are joined together to provide the separation device, but with portions of the joined structure interposed between the flanges of the half-sections, is disclosed in U.S. Pat. No. 3,698,281, entitled "EXPLOSIVE SYSTEM" and issued on Oct. 17, 1972, to O. E. Brandt et al.
U.S. Pat. No. 5,390,606, entitled "FRANGIBLE JOINT SEPARATION SYSTEM", issued on Feb. 21, 1995 to G. N. Harris and which refers to the Brandt et al U.S. Pat. No. 3,698,281, ascribes to it disadvantages including the necessity of forming two separate precision-machined rings to form the structure. In contrast, Harris U.S. Pat. No. 5,390,606 discloses the use of a single-piece, hollow-form extrusion to provide the frangible joint and joinder flanges of the separation device, the core of the hollow-form extrusion having the containment tube containing the linear explosive charge threaded therethrough.
U.S. Pat. No. 5,129,306, entitled "BREAKABLE JOINT SYSTEM ENABLING PARTS TO BE SEPARATED BY MEANS OF AN EXPLOSIVE CHARGE", issued on Jul. 14, 1992 to Gilbert Fauvel discloses a frangible joint system which, as illustrated in FIGS. 4 and 5 of the Fauvel Patent, comprises two half-sections described as an outer plate 21 and an inner plate 22 which are juxtaposed against each other to define between them a housing 23 for receiving an explosive fuse, i.e., an expansion device. The Fauvel Patent specifies that the edges of honeycomb structure parts 30, 31 are hollowed out to receive therein the ends of the joined half-sections which are fastened to the respective structures by bolts 25. The half-sections or plates 21, 22 are configured on their inside surfaces 21D and 22D with recesses so that when joined together a cavity 27 (FIG. 4) of substantially trapezoidal shape extends through the joined structure, as described starting at column 5, line 33 of the Fauvel Patent.
The respective structures of the Brandt et al, Harris and Fauvel Patents are discussed in more detail below.